Such a breathing mask was described in West German Offenlegungsschrift No. DE-OS 30,32,371. A protective mask with a protective helmet located on it is provided there with a fan air inlet means, which ends at the eye level of the mask user, and is provided with a flow indicator there. The air flow is maintained by the fan, and it deflects a vane located at the air outlet end more or less to varying degrees, depending on the output of the fan. The fan air flowing into the interior space of the mask from the rear side of the mask user escapes from the interior space of the mask in the downward direction along an open protective visor that can be folded up. To facilitate reading of the deflected vane, a mirror surface, via which the mask user is able to observe the vane, is arranged on the visor, on its inner side, at the eye level in the visual range.
It is disadvantageous in the known state of the art that the necessary fan output can be monitored only insufficiently or with additional reading aids. A mirror arrangement for reading the position of the vane involves, among others, the risk that due to the mirror-inverted reading, the mask user might erroneously consider an insufficient delivery output to be still sufficient.